​​Some songs rock. Others groove. As examples, I choose Honky tonk woman by the Rolling Stones (a rocker) and Stir it up by Bob Marley and the Wailers (a groover.) Two great tracks.

Rocking​

​In the case of Honky tonk woman, it is Keith Richards who drives the band. If you listen to the original studio version, you can hear him inject energy and ‘boost’ the rhythm at around the 16 second mark. He impatiently plays ahead of Charlie Watts’ steady drum beat, forcing Charlie to step up to meet him. The tempo thus increases slightly. Keith continues to do this throughout the track, with the rest of the band following along behind him. The song’s tempo starts out at around 107bpm and ends up at around 124bpm. That’s quite an increase. If you listen to the start of the track then skip to the end, you will hear the stark contrast in tempo.

Often, energy in a rock context is created in this way, by one player ‘goosing’ the rhythm (to borrow a term used by Miles Davis), i.e., nudging the tempo slightly faster. In The Police, it was Stewart Copeland, the drummer. In Cream, it was Jack Bruce, the bassist. Ginger Baker, Cream’s drummer, complained about Jack’s time-keeping, but, in my opinion, his energy was sadly missing in much of Eric Clapton’s later music, played with very professional and more restrained musicians. In a jazz context, Django Reinhardt, guitar legend, drove the infectious rhythm of his Quintette du Hot Club de France.

If a player rushes ahead of the beat too much, or if the other musicians do not respond by increasing their tempo to meet the rushing player, then the music suffers. The music will seem to be lacking energy, too slow. The intention of the rushing player was to create energy but instead they have reduced energy. I have experienced this phenomenon in amateur cover bands. We often played songs at faster tempos than the original, but they seemed slower. It was an auditory illusion caused by one runaway player sucking the energy away by playing too far ahead of the beat. So, the lesson here is that goosing the rhythm can make for a great rocking track IF done with some degree of subtlety.

Grooving​

​Stir it up is the opposite of Honky tonk. Here, the bassist (either Robbie Shakespeare or Family Man Barrett??) plays a little behind the beat supplied by the other musicians, especially on the verses. It’s milliseconds, but it creates a great groove. And it has the effect of slowing the tempo over the course of the song, but the energy is maintained. The song starts at 152bpm and ends at 146bpm.

Summary​

The interplay of one or more players in a band playing a little ahead or a little behind the beat of the other players can create an energetic rocking rhythm or a cool groove. A player’s stretching of the tempo should be subtle or the song with neither rock nor groove.